1. Field of the Invention
The present invention generally relates to a thrust coupler and, more particularly, to a thrust coupler with a resilient insert that is able to withstand compressive forces.
2. Description of the Prior Art
Many different types of coupling devices are known to those skilled in the art. Typically, the coupling device is connected between two rotatable shafts in a manner that enables the system to transmit torque from a drive shaft to another shaft. In some applications, the two shafts are not coaxial and in some applications the two shafts do not necessarily rotate at precisely the same instantaneous angular velocities at all times. The primary function of any coupling device, such as the one that will be described below in the description of the preferred embodiment of the present invention, is to allow two rotatable shafts to be connected together, typically with flanges, in a manner that transits torque between them. One particular application of this type of coupling device is in a marine propulsion system such as an inboard drive system.
Some coupling devices bolt the metallic flanges of the two shafts directly together. Others place a resilient member between the flanges in order to absorb the forces caused by misalignments of the two shafts and flanges.
A book titled, "Mechanisms & Mechanical Devices Source Book" by Nicholas P. Chironis, was published in 1991 by McGraw-Hill, Inc. Chapter 7, which is titled "Coupling, Clutching and Braking Devices", deals with many types of coupling devices. Chapter 7 provides a summary of these coupling devices along with brief descriptions relating to their structure and theory of operation.
Several companies that manufacture marine propulsion devices describe the alignment procedure in their installation manuals. For example, one such manual is the 1996 installation manual for MerCruiser gasoline ski boat models which incorporate inboard marine propulsion systems.
When used in the marine industry, a typical application of a coupling device incorporates two metallic flanges bolted directly together to connect a propeller shaft to the output shaft of a transmission driven by an internal combustion engine. Typically, the propeller shaft extends through the hull of the boat and has a propeller attached to a distal end thereof. The engine and transmission must be moved and adjusted so that their position causes the output shaft to be aligned coaxially with the propeller shaft which typically has much less freedom of movement relative to the boat hull. If the two shafts are not aligned properly, the propulsion system can exhibit noise and may eventually experience significant damage. The present technique for aligning the two shafts in a marine propulsion system, such as an inboard propulsion system, is to alter various adjustable support brackets to change the position of the internal combustion engine and transmission until the output shaft is coaxial with the propeller shaft. When this occurs, a flange attached to an end of the output shaft is fastened to a flange attached to the end of the propeller shaft.
The procedure described immediately above can be very time consuming and expensive to perform. If it is not properly performed at prescribed intervals of boat usage, damage can occur. It would therefore be significantly beneficial if a coupling device could be developed which is suitable for use in a marine propulsion system, but which does not require the precise alignment accuracy normally required in known marine propulsion systems.